Big Boy, Bird and the Beaver

[ArthurWerner]

2007 Beaver Contessa, 400 iSL.
Plugged into 50amp shore
Go to start the engine, nothing
Engine batteries fully charged
Open the Big Boy compartment and find that is hotter than??? and the seal melted( gotta love the smell of burning electrical components)
Turn to "OFF" the engine battery switch.
This is the third time in about six months.
Changing Big Boy and BIRD at the same time
Any thoughts for an old accountant and NOT mechanic?
Cheers
Arthur(The Walker) Werner

[fkloster]

Welcome Arthur! some questions...
1) what is a Big Boy?
2) what is a BIRD?
3) please specify what was hotter than?
4) what seal melted?

[ArthurWerner]

1) Big Boy relay, when on shore power it toggles to keep the engine batteries and house batteries charged.
2)B.I.R.D. box?? You may want to look it up.
3)HELL
4)the seal at the top of the BigBoy.

[ClassAboater]

Originally Posted by ArthurWerner

2)B.I.R.D. box?? You may want to look it up.

OK, I Googled it. Search came up with all sorts of things about a movie called 'Bird Box'. I don't suppose that is what you are talking about.

So.. I added in RV Part after it. The search came back with all sorts of bird houses for sale on line...

[fkloster]

I just purchased and had installed a Blue Sea ML-ACR rated @ 500 amps. Your intelletec is rated @ 200 amps which should be plenty sufficiant. Perhaps your inverter that is converting the shore power to battery charge is malfunctioning and blowing up your big boy switch.

[twinboat]

It sounds like your starting your engine thru the Big Boy solenoid and overloading it.

The big boy relay is not in the path of the starter circuit, except when the boost switch is pushed.

Disconnect it and find out why the chassis battery isn't starting the engine.
Check the cable from the chassis battery on its path to the starter motor.

You could have a bad disconnect switch blocking the current flow from the chassis battery.

[Jobert]

The B.I.R.D. by intellitec, stands for Bi-Directional Isolater Relay Delay. It is a device, on some a circuit board and some a stand alone device, that controls direction of charge of house and chassis batteries and also connecting them for extra power when needed if one bank gets low on charge. It works in conjunction with a Big Boy Solenoid on many setups to complete that task. This is mostly close to correct but gives enough information for a more in-depth search. Hope this helps. Happy Trails Bert

[ArthurWerner]

In spite of lacking mechanical ability I was able to install the new BigBoy and BIRD box. A few newly AND creatively conjugated profanities success! So far no smoke, no excessive heat. Just wonder what made it go south.

[CountryB]

the contacts inside the Big Boy can get pitted from wear and if any corrosion/moisture builds up due to leaking cover seal. That resistance causes heat and then it just gets hotter/worse from there until complete failure.

There are some threads on this forum regarding disassembly and cleaning of the Big Boy.

Also, note that there are two different Big Boy solenoids - one is an "Isolation" solenoid, the other is a "Disconnect" solenoid. It's easy to confuse them.
Be sure you got the correct one (the Isolation solenoid).

[distaff]

Arthur - good job on posting your model info in the post, many forget to do so. I suggest you add it to your profile so you don't have to.

Something is odd - I've had lots of BIRD and BigBoy fun over the years, but there is no way a failed BIRD/BigBoy should prevent a fully charged set of starter batteries from providing power to the starter.

If you were running a dead short through the BigBoy to a dead house side, your starter batteries would have shown a lower that full charge voltage. If you were on 50 amp shore power, your inverter should have been charging your house side, with the BigBoy providing charging power to the chassis.

I suspect you have something else going on. Full charged chassis batteries should turn the starter.

BTW, there is more to the system than just the BIRD and BigBoy, there are some other solenoids that tie the "Boost" switch on your dash into the circuit - the BigBoy can be closed by either the BIRD or Boost switch. The Boost switch sends full voltage (depending on how much is available somewhere between 9 volts (the minimum that will activate the BigBoy) and 14 volts (charging voltage) to activate the solenoid inside the BigBoy. If this voltage is maintained by holding the Boost swithc more than 30 seconds you will melt the solenoid and the BigBoy will open.

The BIRD unit works differently - it sends an initial activation voltage of between 9 and 14 volts (same as above - depends on how much is actually available) but after the first few seconds of activation it begins to modulate the current. If you put a meter on the inputs you will see an initial voltage of 9-14 then after about 5 seconds it will drop to around 1.5 volts. This keeps the solenoid activated (and the BigBoy closed) without burning out the solenoid.

[vito.a]

How old are your engine start batteries?
What voltage are they when the battery disconnect is off (and sitting for 5 min)?
I'm thinking maybe your engine start batteries (one or more) are bad and you are trying to start it with the boost switch only.
Hope you get it sorted out.

[Ivylog]

You will not melt the BigBoy if you hold the boost more than 30 seconds or even 2 minutes...yes it will get very hot but it does that even after the power is modulated by the bird. Its contacts are the same as your starter solenoid and proned to corrosion, not pitting from lack of use.

[CountryB]

Here's the instructions I saved on disassembly and cleaning of the Big Boy

[YC1]

Originally Posted by twinboat

It sounds like your starting your engine thru the Big Boy solenoid and overloading it.

The big boy relay is not in the path of the starter circuit, except when the boost switch is pushed.

Disconnect it and find out why the chassis battery isn't starting the engine.
Check the cable from the chassis battery on its path to the starter motor.

You could have a bad disconnect switch blocking the current flow from the chassis battery.

Twinboat is on the right path. I do not think the starter goes through the battery switch but may connect to a post on the back of it. Could be wrong of course.

In any case, IF you had to push the boost button to start it and you know for a fact that the engine batteries are ok then there is the path from those to the starter that is not working and could put a big strain on the "big boy". It should be able to handle it fine and getting hot is not an issue as stated.

Where is your "big boy" located? If it is in a battery compartment along the back wall it is a smaller version of the monster that is often in the rear engine compartment of a side radiator rv.

You may have a simple loose connection causing an intermittent issue.

IF you can get it to act up again then you need to get a voltmeter on the large wire that connects to the starter. Run a wire to a safe place to connect your voltmeter.

No have someone hit the starter key but do NOT push the aux start button. The voltage will drop very low if you have a bad connection.